Lockhart admitted that he was surprised by poor performance of the U.S. economy in the first quarter, with gross domestic product (GDP) growth coming in at just 0.1 percent, far below market expectations.

This as recent data releases indicate the economy could have even contracted in the first three months of the year.

"The fact that the number came in as low as it did, and in subsequent revisions could even go lower, is a surprise," he said.

Despite this first-quarter slump, however, Lockhard added that he was confident the U.S. economy was now strengthening in line with his forecast of an annual growth rate of three percent.

His comments come after Fed Chair Janet Yellen said last week that the economy was "on track for solid growth this quarter." Although Yellen also warned that a deterioration in housing or financial markets could alter that scenario.

Fed policy accommodative through 2015: Pro

We do not have a strong, fundamental economy, says Robert Wolf, 32 Advisors CEO, sharing his thoughts about the private sector's view on the economy and Fed policy. We absolutely need corporate tax reform, Wolf adds.

Lockhard, meanwhille, reiterated his initial projections as to when the Fed should consider lifting interest rates.

"I view the second half of 2015 as a personal projection of when the conditions are likely to be right. But it's very important to emphasize that the decision to begin raising rates is a function of the economy, and it really depends on how the economy evolves," Lockhart explained.